Method of manufacturing semiconductor device, substrate processing method, substrate processing apparatus, and recording medium

ABSTRACT

There is provided a technique that includes: forming a film containing Si, O and N or a film containing Si and O on a substrate by performing a cycle a predetermined number of times under a condition where SiCl 4  is not gas-phase decomposed, the cycle including non-simultaneously performing: (a) forming NH termination on a surface of the substrate by supplying a first reactant containing N and H to the substrate; (b) forming a SiN layer having SiCl termination formed on its surface by supplying the SiCl 4  as a precursor to the substrate to react the NH termination formed on the surface of the substrate with the SiCl 4 ; and (c) reacting the SiN layer having the SiCl termination with a second reactant containing O by supplying the second reactant to the substrate

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. Ser. No.16/445,077, filed on Jun. 18, 2019 which is based upon and claims thebenefit of priority from Japanese Patent Application No. 2018-116976,filed on Jun. 20, 2018, the entire contents of which are incorporatedherein by reference.

TECHNICAL FIELD

The present disclosure relates to a method of manufacturing asemiconductor device, a substrate processing apparatus, and a recordingmedium.

BACKGROUND

As an example of processes of manufacturing a semiconductor device, aprocess of forming a film containing silicon (Si), nitrogen (N), andoxygen (O), i.e., a silicon oxynitride film (SiON film), on a substrateis often carried out in the related art.

SUMMARY

The present disclosure provides some embodiments of a technique thatimproves film thickness uniformity of a SiON film or a SiO film formedon a substrate in the plane of the substrate.

According to an embodiment of the present disclosure, there is provideda technique, which includes: forming a film containing Si, O and N or afilm containing Si and O on a substrate by performing a cycle apredetermined number of times under a condition where SiCl₄ is notgas-phase decomposed, the cycle including non-simultaneously performing:(a) forming NH termination on a surface of the substrate by supplying afirst reactant containing N and H to the substrate; (b) forming a SiNlayer having SiCl termination formed on its surface by supplying theSiCl₄ as a precursor to the substrate to react the NH termination formedon the surface of the substrate with the SiCl₄; and (c) reacting the SiNlayer having the SiCl termination with a second reactant containing O bysupplying the second reactant to the substrate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram of a vertical type processfurnace of a substrate processing apparatus suitably used in anembodiment of the present disclosure, in which a portion of the processfurnace is shown in a vertical cross sectional view.

FIG. 2 is a schematic configuration diagram of a vertical type processfurnace of the substrate processing apparatus suitably used in anembodiment of the present disclosure, in which a portion of the processfurnace is shown in a cross sectional view taken along line A-A in FIG.1.

FIG. 3 is a schematic configuration diagram of a controller of thesubstrate processing apparatus suitably used in an embodiment of thepresent disclosure, in which a control system of a controller is shownin a block diagram.

FIG. 4 is a diagram illustrating a film-forming sequence according to anembodiment of the present disclosure.

FIG. 5A illustrates a partial enlarged view of a surface of a substrateafter a first reactant is supplied, FIG. 5B illustrates a partialenlarged view of a surface of a substrate after a precursor is supplied,and FIG. 5C illustrates a partial enlarged view of a surface of asubstrate after a second reactant is supplied.

FIG. 6 is a model diagram illustrating a state of a surface of asubstrate when a precursor is supplied.

FIG. 7 is a diagram illustrating an exemplary modification of afilm-forming sequence according to an embodiment of the presentdisclosure.

FIG. 8 is a diagram illustrating an evaluation result of film thicknessuniformity of a SiON film formed on a substrate in the plane of thesubstrate.

FIG. 9A is a diagram illustrating an evaluation result of filmcomposition of the SiON film formed on the substrate, and FIG. 9B is adiagram illustrating an evaluation result of processing resistance ofthe SiON film formed on the substrate in FIG. 9A.

DETAILED DESCRIPTION Embodiment of the Present Disclosure

An embodiment of the present disclosure will now be described in detailmainly with reference to FIGS. 1 to 6.

(1) Configuration of the Substrate Processing Apparatus

As illustrated in FIG. 1, a process furnace 202 includes a heater 207 asa heating mechanism (temperature adjustment part). The heater 207 has acylindrical shape and is supported by a holding plate so as to bevertically installed. The heater 207 functions as an activationmechanism (an excitation part) configured to thermally activate (excite)a gas.

A reaction tube 203 is disposed inside the heater 207 to be concentricwith the heater 207. The reaction tube 203 is made of a heat resistantmaterial, e.g., quartz (SiO₂), silicon carbide (SiC) or the like, andhas a cylindrical shape with its upper end closed and its lower endopened. A process chamber 201 is formed in a hollow cylindrical portionof the reaction tube 203. The process chamber 201 is configured toaccommodate wafers 200 as substrates. The processing of the wafers 200is performed in the process chamber 201.

Nozzles 249 a and 249 b are installed in the process chamber 201 so asto penetrate a lower sidewall of the reaction tube 203. Gas supply pipes232 a and 232 b are respectively connected to the nozzles 249 a and 249b.

Mass flow controllers (MFCs) 241 a and 241 b, which are flow ratecontrollers (flow rate control parts), and valves 243 a and 243 b, whichare opening/closing valves, are installed in the gas supply pipes 232 aand 232 b sequentially from the corresponding upstream sides of gasflow, respectively. A gas supply pipe 232 c is connected to the gassupply pipe 232 a at the downstream side of the valve 243 a. Gas supplypipes 232 d and 232 e are respectively connected to the gas supply pipe232 b at the downstream side of the valve 243 b. MFCs 241 c, 241 d and241 e and valves 243 c, 243 d and 243 e are respectively installed inthe gas supply pipes 232 c, 232 d and 232 e sequentially from thecorresponding upstream sides of gas flow.

As illustrated in FIG. 2, the nozzles 249 a and 249 b are disposed in aspace with an annular plan-view shape between the inner wall of thereaction tube 203 and the wafers 200 such that the nozzles 249 a and 249b extend upward along an arrangement direction of the wafers 200 from alower portion of the inner wall of the reaction tube 203 to an upperportion of the inner wall of the reaction tube 203. Specifically, thenozzles 249 a and 249 b are installed at a lateral side of a waferarrangement region in which the wafers 200 are arranged, namely in aregion which horizontally surrounds the wafer arrangement region, so asto extend along the wafer arrangement region. Gas supply holes 250 a and250 b for supplying a gas are installed on the side surfaces of thenozzles 249 a and 249 b, respectively. The gas supply holes 250 a and250 b are opened toward the center of the reaction tube 203 so as toallow a gas to be supplied toward the wafers 200. The gas supply holes250 a and 250 b may be formed in a plural number between the lowerportion of the reaction tube 203 and the upper portion of the reactiontube 203.

A precursor (precursor gas), for example, a chlorosilane-based gas whichcontains silicon (Si) and chlorine (Cl), is supplied from the gas supplypipe 232 a into the process chamber 201 via the MFC 241 a, the valve 243a, and the nozzle 249 a. The precursor gas refers to a gaseousprecursor, for example, a gas obtained by vaporizing a precursor whichremains in a liquid state under a room temperature and an atmosphericpressure, or a precursor which remains in a gas state under a roomtemperature and an atmospheric pressure. As the chlorosilane-based gas,it may be possible to use, for example, a tetrachlorosilane (SiCl₄) gas.The SiCl₄ gas contains four chemical bonds (Si—Cl bonds) of Si and Cl inone molecule.

A hydrogen nitride-based gas containing, for example, nitrogen (N) andhydrogen (H), as a first reactant (nitriding agent), is supplied fromthe gas supply pipe 232 b into the process chamber 201 via the MFC 241b, the valve 243 b, and the nozzle 249 b. As the hydrogen nitride-basedgas, it may be possible to use, for example, an ammonia (NH₃) gas. TheNH₃ gas contains three chemical bonds (N—H bonds) of N and H in onemolecule.

A nitrogen (N₂) gas as an inert gas is supplied from the gas supplypipes 232 c and 232 d into the process chamber 201 via the MFCs 241 cand 241 d, the valves 243 c and 243 d, the gas supply pipes 232 a and232 b, and the nozzles 249 a and 249 b. The N₂ gas acts as a purge gas,a carrier gas, a dilution gas, or the like.

An oxidizing gas containing, for example, oxygen (O), as a secondreactant (oxidizing agent), is supplied from the gas supply pipe 232 einto the process chamber 201 via the MFC 241 e, the valve 243 e, the gassupply pipe 232 b, and the nozzle 249 b. As the oxidizing gas, it may bepossible to use, for example, an oxygen (O₂) gas.

A precursor supply system is mainly configured by the gas supply pipe232 a, the MFC 241 a, and the valve 243 a. A first reactant supplysystem is mainly configured by the gas supply pipe 232 b, the MFC 241 b,and the valve 243 b. An inert gas supply system is mainly configured bythe gas supply pipes 232 c and 232 d, the MFCs 241 c and 241 d, and thevalves 243 c and 243 d. A second reactant supply system is mainlyconfigured by the gas supply pipe 232 e, the MFC 241 e, and the valve243 e.

One or all of various supply systems described above may be configuredas an integrated supply system 248 in which the valves 243 a to 243 e,the MFCs 241 a to 241 e, and the like are integrated. The integratedsupply system 248 is connected to each of the gas supply pipes 232 a to232 e so that a supply operation of various kinds of gases into the gassupply pipes 232 a to 232 e, i.e., an opening/closing operation of thevalves 243 a to 243 e, a flow rate adjusting operation by the MFCs 241 ato 241 e or the like, is controlled by a controller 121 which will bedescribed later. The integrated supply system 248 is configured as anintegral type or division type integrated unit, and is also configuredso that it is detachable from the gas supply pipes 232 a to 232 e or thelike, so as to perform maintenance, replacement, expansion or the likeof the integrated supply system 248, on an integrated unit basis.

An exhaust pipe 231 configured to exhaust an internal atmosphere of theprocess chamber 201 is installed at a lower side of the sidewall of thereaction tube 203. A vacuum pump 246 as a vacuum exhaust device isconnected to the exhaust pipe 231 via a pressure sensor 245 as apressure detector (pressure detection part) which detects the internalpressure of the process chamber 201 and an auto pressure controller(APC) valve 244 as a pressure regulator (pressure regulation part). TheAPC valve 244 is configured so that a vacuum exhaust and a vacuumexhaust stop of the interior of the process chamber 201 can be performedby opening and closing the APC valve 244 while operating the vacuum pump246 and so that the internal pressure of the process chamber 201 can beadjusted by adjusting an opening degree of the APC valve 244 based onpressure information detected by the pressure sensor 245 while operatingthe vacuum pump 246. An exhaust system mainly includes the exhaust pipe231, the pressure sensor 245 and the APC valve 244. The vacuum pump 246may be regarded as being included in the exhaust system.

A seal cap 219, which serves as a furnace opening cover configured tohermetically seal a lower end opening of the reaction tube 203, isinstalled under the reaction tube 203. The seal cap 219 is made of ametal material such as, e.g., stainless steel (SUS) or the like, and isformed in a disc shape. An O-ring 220, which is a seal member makingcontact with the lower end portion of the reaction tube 203, isinstalled on an upper surface of the seal cap 219. A rotation mechanism267 configured to rotate a boat 217, which will be described later, isinstalled under the seal cap 219. A rotary shaft 255 of the rotationmechanism 267, which penetrates the seal cap 219, is connected to theboat 217. The rotation mechanism 267 is configured to rotate the wafers200 by rotating the boat 217. The seal cap 219 is configured to bevertically moved up and down by a boat elevator 115 which is an elevatormechanism installed outside the reaction tube 203. The boat elevator 215is configured as a transfer device (transfer mechanism) which loads andunloads (transfers) the wafers 200 into and from (out of) the processchamber 201 by moving the seal cap 219 up and down.

The boat 217 serving as a substrate support is configured to support aplurality of wafers 200, e.g., 25 to 200 wafers, in such a state thatthe wafers 200 are arranged in a horizontal posture and in multiplestages along a vertical direction with the centers of the wafers 200aligned with one another. That is, the boat 217 is configured to arrangethe wafers 200 in a spaced-apart relationship. The boat 217 is made of aheat resistant material such as quartz or SiC. Heat insulating plates218 made of a heat resistant material such as quartz or SiC aresupported below the boat 217 in a horizontal posture and in multiplestages.

A temperature sensor 263 serving as a temperature detector is installedin the reaction tube 203. Based on temperature information detected bythe temperature sensor 263, a state of supplying electric power to theheater 207 is adjusted such that the interior of the process chamber 201has a desired temperature distribution. The temperature sensor 263 isinstalled along the inner wall of the reaction tube 203.

As illustrated in FIG. 3, the controller 121, which is a controller(control means), may be configured as a computer including a centralprocessing unit (CPU) 121 a, a random access memory (RAM) 121 b, amemory device 121 c, and an I/O port 121 d. The RAM 121 b, the memorydevice 121 c and the I/O port 121 d are configured to exchange data withthe CPU 121 a via an internal bus 121 e. An input/output device 122constituted by, e.g., a touch panel or the like, is connected to thecontroller 121.

The memory device 121 c is constituted by, for example, a flash memory,a hard disk drive (HDD), or the like. A control program for controllingoperations of a substrate processing apparatus, a process recipe forspecifying sequences and conditions of a film-forming process asdescribed hereinbelow, or the like is readably stored in the memorydevice 121 c. The process recipe functions as a program for causing thecontroller 121 to execute each sequence in the film-forming process, asdescribed hereinbelow, to obtain a predetermined result. Hereinafter,the process recipe and the control program will be generally and simplyreferred to as a “program.” Further, the process recipe will be simplyreferred to as a “recipe.” When the term “program” is used herein, itmay indicate a case of including only the recipe, a case of includingonly the control program, or a case of including both the recipe and thecontrol program. The RAM 121 b is configured as a memory area (workarea) in which a program, data and the like read by the CPU 121 a istemporarily stored.

The I/O port 121 d is connected to the MFCs 241 a to 241 e, the valves243 a to 243 e, the pressure sensor 245, the APC valve 244, the vacuumpump 246, the temperature sensor 263, the heater 207, the rotationmechanism 267, the boat elevator 115, and the like, as described above.

The CPU 121 a is configured to read the control program from the memorydevice 121 c and execute the same. The CPU 121 a also reads the recipefrom the memory device 121 c according to an input of an operationcommand from the input/output device 122. In addition, the CPU 121 a isconfigured to control, according to the contents of the recipe thusread, the flow rate adjusting operation of various kinds of gases by theMFCs 241 a to 241 e, the opening/closing operation of the valves 243 ato 243 e, the opening/closing operation of the APC valve 244, thepressure regulating operation performed by the APC valve 244 based onthe pressure sensor 245, the driving and stopping of the vacuum pump246, the temperature adjusting operation performed by the heater 207based on the temperature sensor 263, the operation of rotating the boat217 with the rotation mechanism 267 and adjusting the rotation speed ofthe boat 217, the operation of moving the boat 217 up and down with theboat elevator 115, and the like.

The controller 121 may be configured by installing, on the computer, theaforementioned program stored in an external memory device 123. Theexternal memory device 123 may include, for example, a magnetic discsuch as an HDD, an optical disc such as a CD, a magneto-optical discsuch as an MO, a semiconductor memory such as a USB memory, and thelike. The memory device 121 c or the external memory device 123 isconfigured as a computer-readable recording medium. Hereinafter, thememory device 121 c and the external memory device 123 will be generallyand simply referred to as a “recording medium.” When the term “recordingmedium” is used herein, it may indicate a case of including only thememory device 121 c, a case of including only the external memory device123, or a case of including both the memory device 121 c and theexternal memory device 123. Further, the program may be supplied to thecomputer using a communication means such as the Internet or a dedicatedline, instead of using the external memory device 123.

(2) Substrate Processing

A substrate processing sequence example of forming a SiON film on awafer 200 as a substrate using the aforementioned substrate processingapparatus, i.e., a film-forming sequence example, which is one of theprocesses for manufacturing a semiconductor device, will be describedwith reference to FIG. 4. In the following descriptions, the operationsof the respective parts constituting the substrate processing apparatusare controlled by the controller 121.

In the film-forming sequence illustrated in FIG. 4, there are performed:step A of supplying an NH₃ gas as a first reactant containing N and H toa wafer 200 to form NH termination on a surface of the wafer 200; step Bof supplying an NH₃ gas as a first reactant containing N and H to thewafer 200 to form NH termination on a surface of the wafer 200; step Cof supplying a SiCl₄ gas as a precursor to the wafer 200 to react the NHtermination formed on the surface of the wafer 200 with SiCl₄ to form aSiN layer having SiCl termination formed on its surface; and step D ofsupplying an O₂ gas as a second reactant containing O to the wafer 200to react the SiN layer having SiCl termination with the O₂ gas.

Specifically, a cycle which non-simultaneously performs step B, step C,and step D described above under a condition in which SiCl₄ is notgas-phase decomposed after performing step A described above isimplemented a predetermined number of times. Thus, a SiON film is formedon the wafer 200. Furthermore, in FIG. 4, execution periods of steps A,B, C, and D are denoted as A, B, C, and D, respectively.

In the present disclosure, for the sake of convenience, the film-formingsequence illustrated in FIG. 4 may sometimes be denoted as follows.Here, P indicates a purge step of supplying a purge gas to the wafer 200to remove the gas or the like remaining on the wafer 200. The samedenotation will be used in other embodiments and the like as describedhereinbelow.

NH₃→P→(NH₃→P→SiCl₄→P→O₂→P)×n⇒SiON

When the term “wafer” is used herein, it may refer to a wafer itself ora laminated body of a wafer and a predetermined layer or film formed onthe surface of the wafer. In addition, when the phrase “a surface of awafer” is used herein, it may refer to a surface of a wafer itself or asurface of a predetermined layer or the like formed on a wafer.Furthermore, in the present disclosure, the expression “a predeterminedlayer is formed on a wafer” may mean that a predetermined layer isdirectly formed on a surface of a wafer itself or that a predeterminedlayer is formed on a layer or the like formed on a wafer. In addition,when the term “substrate” is used herein, it may be synonymous with theterm “wafer.”

(Wafer Charging and Boat Loading)

A plurality of wafers 200 is charged on the boat 217 (wafer charging).Thereafter, as illustrated in FIG. 1, the boat 217 supporting theplurality of wafers 200 is lifted up by the boat elevator 115 and isloaded into the process chamber 201 (boat loading). In this state, theseal cap 219 seals the lower end of the reaction tube 203 through theO-ring 220.

(Pressure Regulation and Temperature Adjustment)

The interior of the process chamber 201, namely the space in which thewafers 200 are located, is vacuum-exhausted (depressurization-exhausted)by the vacuum pump 246 so as to reach a desired processing pressure(degree of vacuum). In this operation, the internal pressure of theprocess chamber 201 is measured by the pressure sensor 245. The APCvalve 244 is feedback-controlled based on the measured pressureinformation. Furthermore, the wafers 200 in the process chamber 201 areheated by the heater 207 to a desired processing temperature(film-forming temperature). In this operation, the state of supplyingelectric power to the heater 207 is feedback-controlled based on thetemperature information detected by the temperature sensor 263 such thatthe interior of the process chamber 201 has a desired temperaturedistribution. In addition, the rotation of the wafers 200 by therotation mechanism 267 begins. The driving of the vacuum pump 246 andthe heating and rotation of the wafers 200 may be all continuouslyperformed at least until the processing of the wafers 200 is completed.

(Film-Forming Process)

Next, the following steps A to D are sequentially performed.

[Step A]

At this step, an NH₃ gas is supplied to the wafer 200 in the processchamber 201. Specifically, the valve 243 b is opened to allow an NH₃ gasto flow through the gas supply pipe 232 b. The flow rate of the NH₃ gasis adjusted by the MFC 241 b. The NH₃ gas is supplied into the processchamber 201 via the nozzle 249 b and is exhausted from the exhaust pipe231. At this time, the NH₃ gas is supplied to the wafer 200 from theside of the wafer 200. Simultaneously, the valves 243 c and 243 d may beopened to allow an N₂ gas to flow through the gas supply pipes 232 c and232 d.

The processing conditions at this step may be exemplified as follows:

NH₃ gas supply flow rate: 100 to 10,000 sccm

N₂ gas supply flow rate (per gas supply pipe): 0 to 10,000 sccm

Supply time of each gas: 1 to 30 minutes

Processing temperature: 300 to 1,000 degrees C., 700 to 900 degrees C.in some embodiments, or 750 to 800 degrees C. in some embodiments

Processing pressure: 1 to 4,000 Pa or 20 to 1,333 Pa in someembodiments.

Furthermore, in the present disclosure, the expression of the numericalrange such as “300 to 1,000 degrees C.” may mean that a lower limitvalue and an upper limit value are included in that range. Therefore,“300 to 1,000 degrees C.” may mean “300 degrees C. or higher and 1,000degrees C. or lower.” The same applies to other numerical ranges.

A natural oxide film or the like may be formed on the surface of thewafer 200 prior to performing a film-forming process. By supplying theNH₃ gas to the wafer 200 under the aforementioned conditions, NHtermination can be formed on the surface of the wafer 200 on which thenatural oxide film or the like is formed. The NH termination formed onthe surface of the wafer 200 may be regarded as synonymous with an Htermination. Furthermore, since the supply of the NH₃ gas to the wafer200 and the process of forming the NH termination on the surface of thewafer 200 at this step are performed prior to a substantial film-formingprocess (steps B, C and D), they will be referred to as pre-flow andpre-processing, respectively.

In the case where the NH₃ gas is supplied to the wafer 200 from the sideof the wafer 200 as in the present embodiment, there is a tendency thatthe formation of the NH termination starts earlier in an outerperipheral portion of the wafer 200, and starts in the central portionof the wafer 200 with delay. This phenomenon becomes particularlyconspicuous when a pattern including a recess such as a trench or a holeis formed on the surface of the wafer 200. At this step, if the supplytime of the NH₃ gas is less than 1 minute, although the NH terminationmay be formed in the outer peripheral portion of the wafer 200, the NHtermination may be difficult to be formed in the center portion of thewafer 200 (loading effect). By setting the supply time of the NH₃ gas ata time of 1 minute or more, it is possible to form the NH terminationfrom the outer peripheral portion to the central portion of the wafer200 uniformly, i.e., substantially uniformly in amount and density.However, if the supply time of the NH₃ gas exceeds 30 minutes, thesupply of the NH₃ gas to the wafer 200 may be continued in a state inwhich the formation reaction of the NH termination on the surface of thewafer 200 is saturated. As a result, usage amount of the NH₃ gas whichdoes not contribute to the formation of the NH termination unnecessarilyincreases, which may increase a gas cost. By setting the supply time ofthe NH₃ gas at a time of 30 minutes or less, it is possible to suppressan increase in the gas cost.

After the NH termination is formed on the surface of the wafer 200 bypre-flowing the NH₃ gas to the wafer 200, the valve 243 b is closed tostop the supply of the NH₃ gas into the process chamber 201. Then, theinterior of the process chamber 201 is vacuum-exhausted and the gas orthe like remaining within the process chamber 201 is removed from theinterior of the process chamber 201. At this time, the valves 243 c and243 d are opened to supply an N₂ gas as a purge gas into the processchamber 201 (purge step). The processing pressure at the purge step maybe set at a pressure of, for example, 1 to 100 Pa, and the supply flowrate of the N₂ gas may be set at a flow rate of, for example, 10 to10,000 sccm.

As the first reactant, it may be possible to use, in addition to the NH₃gas, a hydrogen nitride-based gas such as a diazene (N₂H₂) gas, ahydrazine (N₂H₄) gas, and an N₃H₈ gas.

As the inert gas, it may be possible to use, in addition to the N₂ gas,a rare gas such as an Ar gas, an He gas, an Ne gas, and an Xe gas. Thisalso applies to steps B, C, and D as described hereinbelow.

[Step B]

At this step, an NH₃ gas is supplied to the wafer 200 in the processchamber 201 as at step A. Specifically, the opening/closing control ofthe valves 243 a to 243 d is performed in the same procedure as theopening/closing control of the valves 243 b to 243 d at step A. The flowrate of the NH₃ gas is controlled by the MFC 241 b. The NH₃ gas issupplied into the process chamber 201 via the nozzle 249 b and isexhausted from the exhaust pipe 231. At this time, the NH₃ gas issupplied to the wafer 200 from the side of the wafer 200.

The processing conditions at this step may be exemplified as follows:

Supply time of NH₃ gas: 1 to 60 seconds, or 1 to 50 seconds in someembodiments.

Other processing conditions may be similar to the processing conditionsof step A.

By supplying the NH₃ gas to the wafer 200 under the aforementionedconditions, NH termination is formed on the surface of the wafer 200 asat step A. Thus, a desired film-forming reaction can go ahead on thewafer 200 at step C as described hereinbelow. A partial enlarged view ofthe surface of the wafer 200 in which the NH termination is formed isillustrated in FIG. 5A. As described above, the NH termination formed onthe surface of the wafer 200 may be regarded as synonymous with an Htermination. Furthermore, at step B in a first cycle, the process offorming the NH termination on the surface of the wafer 200 performed atstep A is complemented. At step B after a second cycle, a process offorming the NH termination on a surface of a SiON layer as describedhereinbelow is performed.

After the NH termination is formed on the surface of the wafer 200, thevalve 243 b is closed to stop the supply of the NH₃ gas into the processchamber 201. Then, the gas or the like remaining within the processchamber 201 is removed from the interior of the process chamber 201under the same processing procedures and processing conditions as thoseof the purge step of step A described above.

As the gas used at this step, it may be possible to use, in addition tothe NH₃ gas, various kinds of hydrogen nitride-based gases exemplifiedat step A described above. Furthermore, it may be possible to usedifferent gases at step A and step B. For example, it may be possible touse the NH₃ gas at step A and the N₂H₂ gas at step B.

[Step C]

At this step, a SiCl₄ gas is supplied to the wafer 200 in the processchamber 201, namely the NH termination formed on the surface of thewafer 200. Specifically, the opening/closing control of the valves 243a, 243 c and 243 d is performed in the same procedure as theopening/closing control of the valves 243 b to 243 d at step A. The flowrate of the SiCl₄ gas is controlled by the MFC 241 a. The SiCl₄ gas issupplied into the process chamber 201 via the nozzle 249 a and isexhausted from the exhaust pipe 231. At this time, the SiCl₄ gas issupplied to the wafer 200 from the side of the wafer 200.

The processing conditions at this step may be exemplified as follows:

SiCl₄ gas supply flow rate: 10 to 2,000 sccm, or 100 to 1,000 sccm insome embodiments

Supply time of SiCl₄ gas: 60 to 180 seconds, or 60 to 120 seconds insome embodiments

Processing temperature: 300 to 1,000 degrees C., 700 to 900 degrees C.in some embodiments, or 750 to 800 degrees C. in some embodiments

Processing pressure: 1 to 2,000 Pa, or 20 to 1,333 Pa in someembodiments.

Other processing conditions may be similar to the processing conditionsof step A.

By supplying the SiCl₄ gas to the wafer 200 under the aforementionedconditions, it is possible to react the NH termination formed on thesurface of the wafer 200 with SiCl₄. Specifically, as illustrated inFIG. 6, Si—Cl bonds in SiCl₄ and N—H bonds in the NH termination formedon the surface of the wafer 200 can be broken. Furthermore, Si after theSi—Cl bonds in SiCl₄ are broken can be bonded to N after the N—H bondsin the NH termination formed on the surface of the wafer 200 are brokento form Si—N bonds. Cl separated from Si and H separated from Nrespectively constitute gaseous substances such as HCl or the like so asto be desorbed from the wafer 200 and are exhausted from the exhaustpipe 231.

In addition, at this step, the Si—Cl bonds, which are not converted intothe Si—N bonds among the Si—Cl bonds in SiCl₄ during the aforementionedreaction, can be held without being broken. That is, at this step, Siafter the Si—Cl bonds in SiCl₄ are broken can be bonded to N after theN—H bonds in the NH termination formed on the surface of the wafer 200are broken in a state where Cl is bonded to each of three bonding handsof four bonding hands of Si constituting SiCl₄.

In the present disclosure, the aforementioned reaction proceeding on thesurface of the wafer 200 at step C will be referred to as an adsorptivesubstitution reaction. At this step, the adsorptive substitutionreaction described above can proceed to form a layer which contains Siand N and whose entire surface is terminated with SiCl, i.e., a siliconnitride layer (SiN layer) having SiCl termination formed on its surface,on the wafer 200. A partial enlarged view of the surface of the wafer200 on which the SiN layer having SiCl termination is formed isillustrated in FIG. 5B. Furthermore, in FIG. 5B, illustration of part ofCl is omitted for the sake of convenience. The SiN layer having SiCltermination becomes a layer in which further Si deposition on the wafer200 does not go ahead even if the supply of the SiCl₄ gas to the wafer200 is further continued after the formation of this layer, due to Clconstituting the SiCl termination acting as steric hindrance. That is,the SiN layer having SiCl termination becomes a layer to whichself-limitation is applied for further Si adsorption reaction.Accordingly, the thickness of the SiN layer becomes a uniform thicknessof less than one atomic layer (less than one molecular layer) over theentire region in the plane of the wafer. Furthermore, the SiCltermination formed on the surface of the wafer 200 may be regarded assynonymous with a Cl termination.

The processing conditions at this step are conditions under which SiCl₄supplied into the process chamber 201 is not gas-phase decomposed(pyrolyzed). That is, the aforementioned processing conditions areconditions under which SiCl₄ supplied into the process chamber 201 doesnot generate an intermediate in the gas phase and the Si deposition onthe wafer 200 by the gas-phase reaction does not go ahead. In otherwords, the processing conditions described above are conditions underwhich only the adsorptive substitution reaction described above canoccur on the wafer 200. By setting the processing conditions at thisstep to such conditions, it is possible to allow the SiN layer formed onthe wafer 200 to become a layer having excellent thickness uniformity inthe plane of the wafer (hereinafter, also simply referred to as in-planethickness uniformity).

If the film-forming temperature (processing temperature) is lower than300 degrees C., there may be a case where it is difficult for the SiNlayer to be formed on the wafer 200 and for the formation of the SiNfilm on the wafer 200 to go ahead at a practical deposition rate.Furthermore, a large amount of impurity such as Cl or the like mayremain in the SiN film formed on the wafer 200, lowering a processingresistance of the SiN film. By setting the film-forming temperature at atemperature of 300 degree C. or higher, the formation of the SiN film onthe wafer 200 can go ahead at a practical deposition rate. In addition,it is possible to allow the SiN film formed on the wafer 200 to become afilm having low impurity concentration and excellent processingresistance. By setting the film-forming temperature at a temperature of700 degrees C. or higher, it is possible to reliably achieve theaforementioned effects. By setting the film-forming temperature at atemperature of 750 degrees C. or higher, it is possible to more reliablyachieve the aforementioned effects.

If the film-forming temperature exceeds 1,000 degrees C., there may be acase where a reaction other than the aforementioned adsorptivesubstitution reaction goes ahead in the process chamber 201. Forexample, the Si—Cl bonds which are not converted into the Si—N bondsamong the Si—Cl bonds in SiCl₄ may be broken, making it difficult to beSiCl-terminated on the entire surface of the SiN layer. That is, it maybe difficult for the SiN layer to become a layer to whichself-limitation is applied for further Si adsorption reaction. Inaddition, SiCl₄ supplied into the process chamber 201 is gas-phasedecomposed (pyrolyzed) to generate an intermediate, and the Sideposition on the wafer 200 by the gas-phase reaction may go ahead. As aresult, the in-plane thickness uniformity of the SiN layer formed on thewafer 200, i.e., the film thickness uniformity of the SiN film in theplane of the substrate (hereinafter, simply referred to as in-plane filmthickness uniformity), may be deteriorated. By setting the film-formingtemperature at a temperature of 1,000 degrees C. or lower, it ispossible to cope with the situations described above. By setting thefilm-forming temperature at a temperature of 900 degrees C. or lower, itis possible to reliably cope with the situations described above. Bysetting the film-forming temperature at a temperature of 800 degrees C.or lower, it is possible to more reliably solve the problems describedabove.

From these facts, the film-forming temperature may be set at 300 to1,000 degrees C., 700 to 900 degrees C. in some embodiments, or 750 to800 degrees C. in some embodiments. Furthermore, among the temperatureconditions illustrated above, the relatively high temperature conditionsuch as, e.g., 700 to 900 degrees C., is a temperature condition underwhich a chlorosilane-based gas such as a dichlorosilane (SiH₂Cl₂,abbreviation: DCS) gas, a hexachlorodisilane (Si₂Cl₆, abbreviation:HCDS) gas or the like is gas-phase decomposed. That is, the DCS gas orHCDS gas may be gas-phase decomposed at 700 to 900 degrees C., and whenthe DCS gas or HCDS gas is supplied to the wafer 200 from the side ofthe wafer 200, the outer peripheral portion of the wafer 200 becomesthick and the gas does not reach the central portion thereof, making itdifficult to achieve the film thickness uniformity. On the other hand,the SiCl₄ gas is not gas-phase decomposed even under a high temperaturecondition in which the DCS gas or the HCDS gas is gas-phase decomposed.Therefore, when performing the film-forming process at this relativelyhigh temperature zone, it can be said that the SiCl₄ gas is a precursorcapable of enhancing the thickness controllability of the SiN filmformed on the wafer 200.

In the case where the SiCl₄ gas is supplied to the wafer 200 from theside of the wafer 200 as in the present embodiment, there is a tendencythat the formation of the SiN layer starts earlier in the outerperipheral portion of the wafer 200, and starts in the central portionof the wafer 200 with delay. This phenomenon becomes particularlyconspicuous when the aforementioned pattern is formed on the surface ofthe wafer 200. At this step, if the supply time of the SiCl₄ gas is lessthan 60 seconds, although the SiN layer may be formed in the outerperipheral portion of the wafer 200, the SiN layer may be difficult tobe formed in the central portion of the wafer 200. By setting the supplytime of the SiCl₄ gas at a time of 60 seconds or more, it is possible toform the SiN layer substantially uniformly, i.e., substantiallyuniformly in thickness and composition, from the outer peripheralportion to the central portion of the wafer 200. However, if the supplytime of the SiCl₄ gas exceeds 180 seconds, the supply of the SiCl₄ gasto the wafer 200 may be continued in a state in which the formationreaction of the SiN layer on the surface of the wafer 200 is saturated.As a result, the usage amount of the SiCl₄ gas which does not contributeto the formation of the SiN layer unnecessarily increases, which mayincrease the gas cost. By setting the supply time of the SiCl₄ gas at atime of 180 seconds or less, it is possible to suppress an increase ingas cost. By setting the supply time of the SiCl₄ gas at a time of 120seconds or less, it is possible to reliably suppress an increase in gascost.

After the SiN layer is formed on the wafer 200, the valve 243 a isclosed to stop the supply of the SiCl₄ gas into the process chamber 201.Then, the gas or the like remaining within the process chamber 201 isremoved from the interior of the process chamber 201 under the sameprocessing procedures and processing conditions as those of the purgestep of step A described above.

[Step D]

At this step, an O₂ gas is supplied to the wafer 200 in the processchamber 201, i.e., the SiN layer having SiCl termination formed on thewafer 200. Specifically, the opening/closing control of the valves 243e, 243 c, and 243 d is performed in the same procedure as theopening/closing control of the valves 243 b to 243 d at step A. The flowrate of the O₂ gas is controlled by the MFC 241 e. The O₂ gas issupplied into the process chamber 201 via the nozzle 249 b and isexhausted from the exhaust pipe 231. At this time, the O₂ gas in anon-plasma-excited state is supplied to the wafer 200 from the side ofthe wafer 200. That is, the O₂ gas thermally excited in a non-plasmaatmosphere is supplied to the wafer 200 from the side of the wafer 200.

The processing conditions at this step may be exemplified as follows:

O₂ gas supply flow rate: 100 to 10,000 sccm

Supply time of O₂ gas: 1 to 120 seconds, or 1 to 50 seconds in someembodiments.

Other processing conditions may be similar to the processing conditionsof step A.

By supplying the O₂ gas to the wafer 200 under the aforementionedconditions, it is possible to modify (oxidize) at least a portion of theSiN layer having SiCl termination formed on the wafer 200 at step C.That is, at least a portion of O components contained in the O₂ gas canbe added to the SiN layer having SiCl termination to form Si—O bonds inthe SiN layer having SiCl termination. The SiN layer having SiCltermination is modified (oxidized) to form a silicon oxynitride layer(SiON layer), which is a layer containing Si, O and N, on the wafer 200.A partial enlarged view of the surface of the wafer 200 on which theSiON layer is formed is illustrated in FIG. 5C. Furthermore, byadjusting the supply time of the O₂ gas, it is possible to adjust the Nconcentration in the SiON layer.

When forming the SiON layer, Cl contained in the SiN layer having SiCltermination constitutes a gaseous substance containing at least Clduring the modification reaction by the O₂ gas, and is discharged fromthe process chamber 201. That is, an impurity such as Cl in the SiNlayer having SiCl termination is separated from the SiN layer havingSiCl termination by being drawn out or desorbed from the SiN layerhaving SiCl termination. In other words, the impurity such as Cl isseparated from the SiN layer, constitutes a gaseous substance such asNH_(x)Cl_(y) or NO_(x) and desorbs from the wafer 200, and is exhaustedfrom the exhaust pipe 231. Thus, the SiON layer becomes a layer having asmall amount of impurity such as Cl, compared with the SiN layer havingSiCl termination.

After the SiON layer is formed, the valve 243 e is closed to stop thesupply of the O₂ gas into the process chamber 201. Then, the gas or thelike remaining within the process chamber 201 is removed from theinterior of the process chamber 201 under the same processing proceduresand processing conditions as those of the purge step of step A describedabove.

As the second reactant, it may be possible to use, in addition to the O₂gas, a non-plasma-excited O-containing gas such as a nitrogen monoxide(NO) gas, a nitrous oxide (N₂O) gas, a nitrogen dioxide (NO₂) gas, acarbon monoxide (CO) gas, a carbon dioxide (CO₂) gas, water vapor (H₂Ogas) or the like.

[Performing a Predetermined Number of Times]

After step A is performed, a cycle which non-simultaneously, i.e.,non-synchronously, performs steps B, C, and D is implemented apredetermined number of times (n times, where n is an integer of 1 ormore), whereby a SiON film having a predetermined thickness can beformed on the wafer 200. Furthermore, the aforementioned cycle may berepeated multiple times. That is, the thickness of the SiON layer formedwhen the cycle which non-simultaneously performs steps B, C, and D isimplemented once may be set smaller than a desired thickness, and theaforementioned cycle may be repeated multiple times until the thicknessof the SiON film formed by laminating the SiON layer becomes equal tothe desired thickness.

Furthermore, in order to allow the SiON film formed on the wafer 200 tobecome a film having excellent in-plane film thickness uniformity, thesupply time of the SiCl₄ gas at step C may be set such that thethickness of the SiN layer formed in the central portion of the wafer200 becomes substantially equal to the thickness of the SiN layer formedin the outer peripheral portion of the wafer 200 in some embodiments. Inother words, the supply time of the SiCl₄ gas at step C may be set for atime so that the amount of the adsorptive substitution reactionoccurring between the NH termination formed on the surface of the wafer200 and the SiCl₄ gas in the central portion of the wafer 200 becomessubstantially equal to the amount of the adsorptive substitutionreaction occurring between the NH termination formed on the surface ofthe wafer 200 and the SiCl₄ gas in the outer peripheral portion of thewafer 200 in some embodiments. For example, by setting the supply timeof the SiCl₄ gas at step C longer than the supply time of the NH₃ gas atstep B, it is possible to reliably achieve the operational effectsdescribed above.

Furthermore, in order to allow the SiON film formed on the wafer 200 tobecome a film having excellent in-plane film thickness uniformity, thesupply time of the NH₃ gas at step A may be set for a time so that theamount or density of the NH termination formed in the central portion ofthe wafer 200 becomes substantially equal to the amount or density ofthe NH termination formed in the outer peripheral portion of the wafer200 in some embodiments. For example, by setting the supply time of theNH₃ gas at step A longer than the supply time of the NH₃ gas at step B,it is possible to reliably achieve the operational effects describedabove. In addition, for example, by setting the supply time of the NH₃gas at step A longer than the supply time of the SiCl₄ gas at step C, itis possible to more reliably achieve the operational effects describedabove.

From this fact, the supply time of the NH₃ gas at step A may be setlonger than the supply time of the SiCl₄ gas at step C, and the supplytime of the SiCl₄ gas at step C may be set longer than the supply timeof the NH₃ gas at step B in some embodiments. Furthermore, the supplytime of the O₂ gas at step D may be set shorter than the supply time ofthe NH₃ gas at step A and longer than the supply time of the NH₃ gas atstep B in some embodiments. By setting the supply times of the variouskinds of gases at steps A, B, C, and D to have such a balance, it ispossible to allow the SiON film formed on the wafer 200 to become a filmhaving very excellent in-plane film thickness uniformity.

(After-Purge and Atmospheric Pressure Return)

After the aforementioned film-forming process is completed, the N₂ gasis supplied from the respective gas supply pipes 232 c and 232 d intothe process chamber 201 and is exhausted from the exhaust pipe 231.Thus, the interior of the process chamber 201 is purged and the gas orthe reaction byproduct, which remains within the process chamber 201, isremoved from the interior of the process chamber 201 (after-purge).Thereafter, the internal atmosphere of the process chamber 201 issubstituted by an inert gas (inert gas substitution). The internalpressure of the process chamber 201 is returned to an atmosphericpressure (atmospheric pressure return).

(Boat Unloading and Wafer Discharging)

Thereafter, the seal cap 219 is moved down by the boat elevator 115 toopen the lower end of the reaction tube 203. Then, the processed wafers200 supported on the boat 217 are unloaded from the lower end of thereaction tube 203 to the outside of the reaction tube 203 (boatunloading). The processed wafers 200 are discharged from the boat 217(wafer discharging).

(3) Effects According to the Present Embodiment

According to the present embodiment, one or more effects as set forthbelow may be achieved.

(a) By implementing a cycle a predetermined number of times under thecondition where SiCl₄ is not gas-phase decomposed after performing stepA, the cycle including non-simultaneously performing step B, step C andstep D, it is possible to allow the SiON film formed on the wafer 200 tobecome a film having excellent in-plane film thickness uniformity.

This is because, by performing step C under the aforementionedconditions, i.e., under the conditions in which only the adsorptivesubstitution reaction occurs between the NH termination formed on thesurface of the wafer 200 and SiCl₄, it is possible to allow the SiNlayer formed on the wafer 200 to become a layer whose entire surface isterminated with SiCl. That is, it is possible to allow the SiN layer tobecome a layer to which self-limitation is applied for further Siadsorption reaction, i.e., for further adsorptive substitution reaction.As a result, it is possible to allow the SiN layer formed on the wafer200 to become a layer having excellent in-plane thickness uniformity.This also makes it possible to allow the SiON layer formed by modifying(oxidizing) the SiN layer to become a layer having excellent in-planethickness uniformity at subsequent step D.

As described above, according to the present embodiment, only the NHtermination formed on the wafer 200 and the SiCl termination formed onthe wafer 200 can be allowed to utilize a film-forming mechanism whichcontributes to the formation of the SiON film on the wafer 200. As aresult, it is possible to allow the SiON film formed on the wafer 200 tobecome a film having excellent in-plane film thickness uniformity.

(b) By setting the supply time of the SiCl₄ gas at step C longer thanthe supply time of the NH₃ gas at step B, it is possible to allow theSiN layer having SiCl termination formed on its surface formed on thewafer 200 to become a layer having excellent in-plane thicknessuniformity. As a result, it is possible to allow the SiON film formed onthe wafer 200 to become a film having excellent in-plane film thicknessuniformity. That is, it is possible to improve the loading effect(substrate surface area dependency).

(c) By setting the supply time of the NH₃ gas at step A longer than thesupply time of the NH₃ gas at step B, it is possible to uniformly formthe NH termination from the outer peripheral portion to the centralportion of the surface of the wafer 200 before the substantialfilm-forming process. This makes it possible to allow the SiN layerformed on the wafer 200 to become a layer having excellent in-planethickness uniformity. As a result, it is possible to allow the SiON filmformed on the wafer 200 to become a film having excellent in-plane filmthickness uniformity.

In addition, by setting the supply time of the NH₃ gas at step A longerthan the supply time of the SiCl₄ gas at step C, it is possible to morereliably achieve the aforementioned effects.

Furthermore, by setting the supply time of the NH₃ gas at step A longerthan the supply time of the O₂ gas at step D, it is possible to morereliably achieve the aforementioned effects.

(d) Since the SiCl₄ gas is used as the precursor, although step C isperformed under a relatively high temperature condition (temperaturecondition of 700 degrees C. or higher) in which the DCS gas or HCDS gasis gas-phase decomposed, it is possible to allow the thickness of theSiN layer formed at that time to become a uniform thickness of less thanone atomic layer (less than one molecular layer) over the entire regionin the plane of the wafer. Therefore, it is possible to precisely andstably control the thickness of the SiON film even under a relativelyhigh temperature condition. That is, it is possible to allow theformation of the SiON film on the wafer 200 to go ahead with enhancedcontrollability even under a relatively high temperature condition andto improve the processing resistance (HF resistance) of the SiON film asa high temperature is possible.

Furthermore, when the DCS gas or HCDS gas is used as the precursor, forexample, under a relatively high temperature condition of 700 degrees C.or higher, the precursor is gas-phase decomposed and the Si-containinglayer formed on the wafer 200 by supplying the precursor becomes a layerto which self-limitation is not applied for further Si adsorptionreaction. Therefore, it is difficult to allow the thickness of theSi-containing layer formed by supplying these precursors to become auniform thickness of less than one atomic layer (less than one molecularlayer) over the entire region in the plane of the wafer under arelatively high temperature condition. That is, when these precursorsare used, the gas-phase reaction becomes dominant and an excessgas-phase reaction occurs under a relatively high temperature condition,making it impossible to improve the loading effect. As a result, it isdifficult to precisely and stably control the thickness of the finallyobtained SiON film. Furthermore, although the film thickness uniformityis achieved by film formation under the temperature conditions in whichthe precursors are not gas-phase decomposed, the processing resistance(HF resistance) may be deteriorated compared with the presentdisclosure.

(e) By using the second reactant in a non-plasma-excited state at stepD, it is possible to suppress oxidation of the SiN layer having SiCltermination formed at step C, and to easily partially remain N withoutcompletely desorbing N from the SiN layer. This makes it possible toform the SiON film of an appropriate composition on the wafer 200.

In addition, by controlling the oxidizing gas supply conditions such asthe supply time of the O₂ gas, the supply flow rate of the O₂ gas, theprocessing pressure, and the type of the oxidizing gas at step D, it ispossible to control the composition ratio of O and N in the SiON film.This makes it possible to control the processing resistance (HFresistance) of the SiON film as formed.

(f) The effects mentioned above can be similarly achieved in the casewhere the aforementioned hydrogen nitride-based gas other than the NH₃gas is used as the first reactant, or in the case where theaforementioned oxidizing gas other than the O₂ gas is used as the secondreactant, or in the case where the aforementioned inert gas other thanthe N₂ gas is used.

OTHER EMBODIMENTS

While the embodiments of the present disclosure have been specificallydescribed above, the present disclosure is not limited to theaforementioned embodiment but may be variously modified withoutdeparting from the spirit of the present disclosure.

For example, the purge step after the pre-flow of the NH₃ gas at step A(purge step between the pre-flow of the NH₃ gas at step A and the supplyof the NH₃ gas at step B) may be omitted. That is, as illustrated inFIG. 7 or in the following film-forming sequence example, the pre-flowof the NH₃ gas at step A and the supply of the NH₃ gas at step B may becontinuously performed. Thus, the same effects as those of thefilm-forming sequence illustrated in FIG. 4 can be achieved, andfurther, the total processing time can be shortened and the productivitycan be improved.

NH₃→(NH₃→P→SiCl₄→P→O₂→P)×n⇒SiON

Furthermore, for example, at at least one of step A and step B, aplasma-activated (excited) NH₃ gas, i.e., a first reactant in aplasma-excited state, may be supplied to the wafer 200. Even in thiscase, the same effects as those of the film-forming sequence illustratedin FIG. 4 may be achieved.

In addition, for example, at step D, a plasma-activated (excited) O₂gas, i.e., a second reactant in a plasma-excited state, may be supplied.Even in this case, the same effects as those of the film-formingsequence illustrated in FIG. 4 may be achieved. Moreover, in this case,the oxidizing power of the second reactant can be enhanced, and at stepD, the SiN layer having SiCl termination formed on the wafer 200 at stepC can be oxidized to form a silicon oxide layer (SiO layer), which is alayer containing Si and O, on the wafer 200. In this case, a SiO filmhaving a predetermined thickness can be formed on the wafer 200 byperforming the aforementioned cycle a predetermined number of times. Inaddition, the oxidizing power of the second reactant can be increasedeven when an O₃ gas), an H₂ gas+O₂ gas, an H₂ gas+O₃ gas), or the likeis used as the second reactant, and at step D, the SiO layer can beformed on the wafer 200. A SiO film having a predetermined thickness canbe formed on the wafer 200 by performing the aforementioned cycle apredetermined number of times.

Furthermore, for example, as illustrated in the following film-formingsequence example, a SiN layer is formed by implementing a set whichnon-simultaneously performs steps B and C a predetermined number oftimes (n₁ times, where n₁ is an integer of 1 or more), and thereafter, aSiON layer is formed by oxidizing the SiN layer by performing step D,and this is defined as one cycle and a SiON film may be formed on thewafer 200 by performing this cycle a predetermined number of times (n₂times, where n₂ is an integer of 1 or more). Even in this case, the sameeffects as those of the film-forming sequence illustrated in FIG. 4 maybe achieved. In addition, in this case, by controlling theaforementioned set number (n₁), it is possible to enhance thecontrollability of control of N concentration and Si concentration to Oconcentration in the SiON film as formed, i.e., control of compositionratio of the SiON film.

NH₃→P→[(NH₃→P→SiCl₄→P)×n→O₂→P]×n ₂⇒SiON

NH₃→[(NH₃→P→SiCl₄→P)×n ₁→O₂→P]×n ₂⇒SiON

Furthermore, step A is particularly effective when the state of anunderlayer (wafer surface) on which a film is formed is in a state inwhich a film is difficult to be formed, but step A may be omitteddepending on a surface state of the wafer.

For example, as illustrated in the following film-forming sequenceexample, a SiON film having a predetermined thickness may be formed onthe wafer 200 by implementing a cycle which non-simultaneously performssteps B, C, and D, without performing step A, a predetermined number oftimes (n times, where n is an integer of 1 or more). Even in this case,the same effects as those of the film-forming sequence illustrated inFIG. 4 may be achieved.

(NH₃→P→SiCl₄→P→O₂→P)×n⇒SiON

Furthermore, for example, as illustrated in the following film-formingsequence example, a SiN layer is formed by implementing a set whichnon-simultaneously performs steps B and C a predetermined number oftimes (n₁ times, where n₁ is an integer of 1 or more), and thereafter, aSiON layer is formed by oxidizing the SiN layer by performing step D,and this is defined as one cycle and a SiON film may be formed on thewafer 200 by performing this cycle a predetermined number of times (n₂times, where n₂ is an integer greater than or equal to 1). Even in thiscase, the same effects as those of the film-forming sequence illustratedin FIG. 4 may be achieved. In addition, in this case, by controlling theaforementioned set number (n₁), it is possible to enhance thecontrollability of control of N concentration and Si concentration to Oconcentration in the SiON film as formed, i.e., control of compositionratio of SiON film.

[(NH₃→P→SiCl₄→P)×n ₁→O₂→P]×n ₂⇒SiON

Recipes used in substrate processing may be prepared individuallyaccording to the processing contents and may be stored in the memorydevice 121 c via a telecommunication line or an external memory device123. Moreover, at the start of substrate processing, the CPU 121 a mayproperly select an appropriate recipe from the recipes stored in thememory device 121 c according to the processing contents. Thus, it ispossible for a single substrate processing apparatus to form films ofdifferent kinds, composition ratios, qualities and thicknesses withenhanced reproducibility. In addition, it is possible to reduce anoperator's burden and to quickly start the substrate processing whileavoiding an operation error.

The recipes mentioned above are not limited to newly-prepared ones butmay be prepared by, for example, modifying the existing recipes alreadyinstalled in the substrate processing apparatus. When modifying therecipes, the modified recipes may be installed in the substrateprocessing apparatus via a telecommunication line or a recording mediumstoring the recipes. In addition, the existing recipes already installedin the substrate processing apparatus may be directly modified byoperating the input/output device 122 of the existing substrateprocessing apparatus.

In the aforementioned embodiments, there has been described an examplein which films are formed using a batch-type substrate processingapparatus capable of processing a plurality of substrates at a time. Thepresent disclosure is not limited to the aforementioned embodiments butmay be appropriately applied to, e.g., a case where films are formedusing a single-wafer-type substrate processing apparatus capable ofprocessing a single substrate or several substrates at a time. Inaddition, in the aforementioned embodiments, there have been describedexamples in which films are formed using the substrate processingapparatus provided with a hot-wall-type process furnace. The presentdisclosure is not limited to the aforementioned embodiments but may beappropriately applied to a case where films are formed using a substrateprocessing apparatus provided with a cold-wall-type process furnace.

In the case of using these substrate processing apparatuses, afilm-forming process may be performed by the processing procedures andprocessing conditions similar to those of the embodiments andmodifications described above. Effects similar to those of theembodiments and modifications described above may be achieved.

The embodiments, modifications and the like described above may beappropriately combined with one another. The processing procedures andprocessing conditions at this time may be similar to, for example, theprocessing procedures and processing conditions of the aforementionedembodiment.

EXAMPLES First Example

In example 1, a SiON film was formed on a wafer using the substrateprocessing apparatus illustrated in FIG. 1 and by the film-formingsequence illustrated in FIG. 4. As the wafer, a bare wafer in which nopattern is formed on its surface, and a pattern wafer in which a patternis formed on its surface and which has a surface area 23 times thesurface area of the bare wafer were used. The processing conditions ateach step were set to predetermined conditions which fall within theprocessing condition range in the aforementioned embodiments.

In a comparative example, after performing step A of the film-formingsequence illustrated in FIG. 4 to form NH termination on the wafer usingthe substrate processing apparatus illustrated in FIG. 1, a cycle isperformed a predetermined number of times, the cycle includingnon-simultaneously performing a step B′ of supplying an HCDS gas to thewafer, a step C′ of supplying an NH₃ gas to the wafer, and a step D′ ofsupplying an O₂ gas to the wafer, whereby a SiON film was formed on thewafer. As the wafer, the aforementioned bare wafer and theaforementioned pattern wafer were used. The processing conditions atsteps A, B′, C′ and D′ were similar to the processing conditions ofsteps A to D of the example, respectively.

Then, the in-plane film thickness uniformities of the SiON film formedin the example and the comparative example were measured. Themeasurement results are shown in FIG. 8. The vertical axis in FIG. 8indicates an in-plane film thickness uniformity (%) of the SiON film.When the value of the in-plane film thickness uniformity (%) is 0, itmeans that the thickness of the SiON film is uniform from the centralportion to the outer peripheral portion of the wafer. When the value ofthe in-plane film thickness uniformity (%) is larger than 0, it meansthat the thickness of the SiON film has a distribution which is thelargest in the central portion of the wafer surface and is graduallydecreased toward the outer peripheral portion thereof, i.e., a centralconvex distribution. When the value of the in-plane film thicknessuniformity (%) is smaller than 0, it means that the thickness of theSiON film has a distribution which is the largest in the outerperipheral portion of the wafer surface and is gradually decreasedtoward the central portion thereof, i.e., a central concavedistribution. In addition, the value of the in-plane film thicknessuniformity (%) indicates that the in-plane film thickness uniformity ofthe SiON film formed on the wafer is better as it approaches zero. Thehorizontal axis in FIG. 8 indicates a case where a bare wafer is used asthe wafer and a case where a pattern wafer is used as the wafer. In FIG.8, a white columnar graph indicates a comparative example, and a shadedcolumnar graph indicates an example.

According to FIG. 8, it can be seen that the in-plane film thicknessuniformity of the SiON film in the example is better than the in-planefilm thickness uniformity of the SiON film in the comparative example inany of the case where the bare wafer is used as the wafer and the casewhere the pattern wafer is used as the wafer. In contrast, it can beseen that the in-plane film thickness uniformity of the SiON film in thecomparative example shows a strong central convex distribution when thebare wafer is used as the wafer and a strong central concavedistribution when the pattern wafer is used as the wafer. That is, it isunderstood that the influence of the surface area of the wafer on thein-plane film thickness uniformity can be suppressed such that theinfluence is lower in the SiON film in the example than in the SiON filmin the comparative example. In other words, it is understood that thefilm-forming method in the example can suppress the so-called loadingeffect (substrate surface area dependency) such that it is lower than inthe film-forming method in the comparative example.

Example 2

In this example, a SiON film or the like was formed on a wafer using thesubstrate processing apparatus illustrated in FIG. 1 and by thefilm-forming sequence illustrated in FIG. 4. At that time, samples 1 to5 such as a plurality of SiON films having different composition ratioswere produced by changing the processing conditions (oxidizing gassupply conditions) at step D. Then, atomic concentrations of Si, N, andO of each film of samples 1 to 5 were measured by X-ray photoelectronspectroscopy (XPS). Furthermore, a wet etching rate (WER) when etchingeach film of samples 1 to 5 using a hydrogen fluoride aqueous solution(DHF solution) diluted to 1% was measured. FIG. 9A is a diagramillustrating a composition ratio of Si, N, and O in each film of samples1 to 5 measured by XPS. In FIG. 9A, the vertical axis indicates anatomic concentration (Atomic %) of each element, and the horizontal axisindicates samples 1 to 5. FIG. 9B is a diagram illustrating a WER ofeach film of samples 1 to 5. In FIG. 9B, the vertical axis indicates aWER (Å/min), and the horizontal axis indicates samples 1 to 5.

The processing conditions (oxidizing gas supply conditions) at step Dwhen producing samples 1 to 5 are as follows. An O₂ gas supply flowrate: 0 slm and a supply time of an O₂ gas: 0 second mean that step Dwas not performed. Other processing conditions were set to predeterminedconditions which fall within the processing condition range of theaforementioned embodiments.

(Sample 1)

O₂ gas supply flow rate: 0 slm

Supply time of O₂ gas: 0 seconds

(Sample 2)

O₂ gas supply flow rate: 3 to 5 slm

Supply time of O₂ gas: 10 to 15 seconds

Processing pressure: 500 to 1,000 Pa

(Sample 3)

O₂ gas supply flow rate: 3 to 5 slm

Supply time of O₂ gas: 100 to 120 seconds

Processing pressure: 500 to 1,000 Pa

(Sample 4)

O₂ gas supply flow rate: 3 to 5 slm

Supply time of O₂ gas: 100 to 120 seconds

Processing pressure: 2,000 to 3,000 Pa

(Sample 5)

H₂ gas supply flow rate: 0.5 to 2 slm

Supply time of O₂ gas: 3 to 5 slm

Supply time of H₂ gas+O₂ gas: 20 to 30 seconds

Processing pressure: 50 to 200 Pa

As illustrated in FIG. 9A, in sample 1 which is a reference sample,although step D was not performed, it was confirmed that an O componentis contained in a film. This is considered to be because the surface ofthe film is oxidized by exposing the film to the atmosphere after filmformation. Furthermore, as illustrated in the measurement results ofsample 2 and sample 3 in FIG. 9A, it was confirmed that the compositionratio of O in the SiON film formed on the wafer can be increased and thecomposition ratio of N can be lowered by prolonging the processing timeat step D. In addition, as illustrated in the measurement results ofsample 3 and sample 4 in FIG. 9A, it was confirmed that the compositionratio of O in the SiON film formed on the wafer can be further increasedand the composition ratio of N can be further lowered by increasing theprocessing pressure at step D. Moreover, as illustrated in themeasurement result of sample 5 in FIG. 9A, it was confirmed that,although the processing time is set shorter than that of samples 3 and 4and the processing pressure is set lower than that of samples 2 to 4 bysupplying an H₂ gas+O₂ gas instead of supplying the O₂ gas at step D,the composition ratio of O in the film formed on the wafer can befurther increased and the composition ratio of N can be further lowered(composition ratio of N can be set to zero). In addition, it wasconfirmed that sample 5 becomes a SiO film rather than a SiON film. Thatis, it was confirmed that the composition ratio of O and N in the SiONfilm can be controlled by controlling the oxidizing gas supplyconditions such as the processing time, the processing pressure, and thegas type at step D.

Furthermore, as illustrated in FIG. 9B, it was confirmed that the lowerthe composition ratio of O in the film is and the higher the compositionratio of N is, the smaller the WER is (the higher HF resistance is).Further, the higher the composition ratio of O in the film is and thelower the composition ratio of N is, the larger the WER is (the lowerthe HF resistance is). That is, it was confirmed that the compositionratio of O and N in the SiON film can be controlled by controlling theoxidizing gas supply conditions at step D, whereby the processingresistance (HF resistance) of the film can be controlled.

According to the present disclosure in some embodiments, it is possibleto improve film thickness uniformity of a SiON film or a SiO film formedon a substrate in the plane of the substrate.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the embodiments described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the embodiments describedherein may be made without departing from the spirit of the disclosures.The accompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thedisclosures.

What is claimed is:
 1. A method of manufacturing a semiconductor device,comprising: forming a film containing Si, O, and N or a film containingSi and O on a substrate by performing a cycle a predetermined number oftimes, the cycle including: (a) forming NH termination on a surface ofthe substrate by supplying a first reactant containing N and H to thesubstrate; (b) forming a Si- and N-containing layer having SiCltermination formed on its surface by supplying SiCl₄ as a precursor tothe substrate to cause the NH termination formed on the surface of thesubstrate to react with the SiCl₄ under a condition in which thereaction of the NH termination and the SiCl₄ is self-limited; and (c)causing the Si- and N-containing layer having the SiCl termination toreact with a second reactant containing O by supplying the secondreactant to the substrate.
 2. The method according to claim 1, wherein(b) is performed under a condition in which the SiCl₄ is not pyrolyzed.3. The method according to claim 1, wherein (b) is performed under acondition in which the SiCl₄ is not gas-phase decomposed.
 4. The methodaccording to claim 1, wherein (b) is performed under a condition inwhich no gas-phase reaction occurs.
 5. The method according to claim 1,wherein (b) is performed under a condition in which SiCl₄ does notgenerate an intermediate in gas phase.
 6. The method according to claim1, wherein (b) is performed under a condition in which an adsorptivesubstitution reaction occurs between the NH termination formed on thesurface of the substrate and the SiCl₄.
 7. The method according to claim1, wherein (b) is performed under a condition in which Si—N bonds areformed by bonding of Si constituting the SiCl₄ and N constituting the NHtermination formed on the surface of the substrate, and at that time,Si—Cl bonds which are not converted into the Si—N bonds among Si—Clbonds contained in the SiCl₄ are held without being broken.
 8. Themethod according to claim 1, wherein (b) is performed under a conditionin which at least a portion of Si—Cl bonds in the SiCl₄ and at least aportion of N—H bonds in the NH termination formed on the surface of thesubstrate are broken, and Si—N bonds are formed by bonding of Si afterat least the portion of the Si—Cl bonds in the SiCl₄ are broken and Nafter at least the portion of the N—H bonds in the NH termination formedon the surface of the substrate are broken, and at that time, Si—Clbonds which are not converted into the Si—N bonds among the Si—Cl bondsin the SiCl₄ are held without being broken.
 9. The method according toclaim 1, wherein (b) is performed under a condition in which Siconstituting the SiCl₄ is bonded to N constituting the NH terminationformed on the surface of the substrate in a state in which Cl is bondedto each of three bonding hands among four bonding hands of Siconstituting the SiCl₄.
 10. The method according to claim 1, wherein (b)is performed under a condition in which Si after at least a portion ofSi—Cl bonds in the SiCl₄ are broken is bonded to N after at least aportion of N—H bonds in the NH termination formed on the surface of thesubstrate are broken in a state in which Cl is bonded to each of threebonding hands among four bonding hands of Si constituting the SiCl₄. 11.The method according to claim 1, wherein a supply time of the SiCl₄ in(b) is set longer than a supply time of the first reactant in (a). 12.The method according to claim 1, further comprising (d) supplying thefirst reactant to the substrate before performing the cycle thepredetermined number of times.
 13. The method according to claim 11,wherein a supply time of the first reactant in (d) is set longer than asupply time of the first reactant in (a).
 14. The method according toclaim 11, wherein a supply time of the first reactant in (d) is setlonger than a supply time of the SiCl₄ in (b).
 15. The method accordingto claim 1, wherein a supply time of the SiCl₄ in (b) is set such thatan amount of an adsorptive substitution reaction occurring between theNH termination formed on the surface of the substrate and the SiCl₄ in acentral portion of the substrate becomes substantially equal to anamount of an adsorptive substitution reaction occurring between the NHtermination formed on the surface of the substrate and the SiCl₄ in anouter peripheral portion of the substrate.
 16. The method according toclaim 1, wherein a supply time of the SiCl₄ in (b) is set such that athickness of the Si- and N-containing layer formed in a central portionof the substrate becomes substantially equal to a thickness of the Si-and N-containing layer formed in an outer peripheral portion of thesubstrate.
 17. The method according to claim 1, wherein in (a), thefirst reactant is supplied to the substrate from a side of thesubstrate, wherein, in (b), the SiCl₄ is supplied to the substrate fromthe side of the substrate, and wherein, in (c), the second reactant issupplied to the substrate from the side of the substrate.
 18. Asubstrate processing method, comprising: forming a film containing Si,O, and N or a film containing Si and O on a substrate by performing acycle a predetermined number of times, the cycle including: (a) formingNH termination on a surface of the substrate by supplying a firstreactant containing N and H to the substrate; (b) forming a Si- andN-containing layer having SiCl termination formed on its surface bysupplying SiCl₄ as a precursor to the substrate to cause the NHtermination formed on the surface of the substrate to react with theSiCl₄ under a condition in which the reaction of the NH termination andthe SiCl₄ is self-limited; and (c) causing the Si- and N-containinglayer having the SiCl termination to react with a second reactantcontaining O by supplying the second reactant to the substrate.
 19. Asubstrate processing apparatus, comprising: a process chamber in which asubstrate is processed; a first reactant supply system configured tosupply a first reactant containing N and H to the substrate in theprocess chamber; a precursor supply system configured to supply SiCl₄ asa precursor to the substrate in the process chamber; a second reactantsupply system configured to supply a second reactant containing O to thesubstrate in the process chamber; a heater configured to heat thesubstrate in the process chamber; and a controller configured to becapable of controlling the first reactant supply system, the precursorsupply system, the second reactant supply system, and the heater toperform a process in the process chamber, the process comprising:forming a film containing Si, O, and N or a film containing Si and O onthe substrate by performing a cycle a predetermined number of times, thecycle including: (a) forming NH termination on a surface of thesubstrate by supplying the first reactant to the substrate; (b) forminga Si- and N-containing layer having SiCl termination formed on itssurface by supplying the SiCl₄ to the substrate to cause the NHtermination formed on the surface of the substrate to react with theSiCl₄ under a condition in which the reaction of the NH termination andthe SiCl₄ is self-limited; and (c) causing the Si- and N-containinglayer having the SiCl termination to react with the second reactant bysupplying the second reactant to the substrate.
 20. A non-transitorycomputer-readable recording medium storing a program that causes, by acomputer, a substrate processing apparatus to perform a process, theprocess comprising: forming a film containing Si, O, and N or a filmcontaining Si and O on a substrate by performing a cycle a predeterminednumber of times, the cycle including: (a) forming NH termination on asurface of the substrate by supplying a first reactant containing N andH to the substrate; (b) forming a Si- and N-containing layer having SiCltermination formed on its surface by supplying SiCl₄ as a precursor tothe substrate to cause the NH termination formed on the surface of thesubstrate to react with the SiCl₄ under a condition in which thereaction of the NH termination and the SiCl₄ is self-limited; and (c)causing the Si- and N-containing layer having the SiCl termination toreact with a second reactant containing O by supplying the secondreactant to the substrate.